Everytime i load my project, the material is missing
You can "pack" the image into the .blend file so that you don't have to worry about the external files moving around. You do do this from the image editor, under the "image" dropdown menu (pack is the last option).

Keep in mind that it will actually save the image into the blend file, so if you did this with, say, a 10mb png file, and you save multiple versions of the blend file, they will all include the 10mb png as well.